Face masks and respirators find utility in a variety of manufacturing, custodial, and household applications by protecting the wearer from inhaling dust and other harmful airborne contaminates through their mouth or nose. Likewise, the use of face masks is a recommended practice in the healthcare industry to help prevent the spread of disease. Face masks worn by healthcare providers help reduce infections in patients by filtering the air exhaled from the wearer thus reducing the number of harmful organisms or other contaminants released into the environment.
This is especially important during surgeries where the patient is much more susceptible to infection due to the open wound site. Similarly, patients with respiratory infections may use face masks to prevent the spread of disease by filtering and containing any expelled germs. Additionally, face masks protect the healthcare worker by filtering airborne contaminants and microorganisms from the inhaled air.
Some diseases, such as hepatitis and AIDS, can be spread through contact of infected blood or other body fluids to another person's mucous membranes, ie. eyes, nose, mouth, etc. The healthcare industry recommends specific practices to reduce the likelihood of contact with contaminated body fluids. One such practice is to use face masks which are resistant to penetration from a splash of body fluids.
The section of the face mask that covers the nose and mouth is typically known as the front panel or body portion. The body of the mask can be comprised of several layers of material. At least one layer is composed of a filtration material (filtration media layer) that prevents the passage of germs and other contaminants therethrough but allows for the passage of air so that the user may comfortably breathe. The porosity of the mask refers to how easily air is drawn through the mask. A more porous mask is easier to breathe through. The body portion may also contain multiple layers to provide additional functionality or attributes to the face mask. For example, many face masks include a layer of material on either side of the filtration media layer. The layer that contacts the face of the wearer is typically referred to as the inner facing. The layer furthest from the face is referred to as the outer facing.
Face masks have also been designed to seal around the perimeter of the mask to the face of the wearer. Such a sealing arrangement is intended to force all exchanges of air through the body of the mask in order to prevent airborne pathogens and/or infectious fluids from being transferred to and/or from the wearer.
Attached to the body section are devices to hold the body section securely to the head of the user. For instance, manual tie straps that extend around the user's head and are tied at the back of the wearer's head are typically used in masks worn in surgeries. Respirators used for healthcare typically employ elastic bands that wrap around the head and hold the body section firmly to the face to ensure a tight seal. Masks that use loops that wrap around the wearer's ears are typically used in non-surgical healthcare situations such as isolation wards or by dental hygienists.
As stated, face masks may be designed to be resistant to penetration by splashes of fluids so that pathogens found in blood or other fluids are not able to be transferred to the nose, mouth, and/or skin of the user of the face mask. The American Society of Testing and Materials has developed test method F-1862, “Standard Test Method of Resistance of Medical Face Masks to Penetration by Synthetic Blood (Horizontal Projection of Fixed Volume at a Known Velocity) to assess a face mask's ability to resist penetration by a splash. The splash resistance of a face mask is typically a function of the ability of the layer or layers of the face mask to resist fluid penetration, and/or their ability to reduce the transfer of the energy of the fluid splash to subsequent layers, and/or by their ability to absorb the energy of the splash. Typical approaches to improving fluid resistance are to use thicker materials or additional layers in the construction of the face mask. However, these solutions may increase the cost of the face mask and reduce the porosity of the face mask.
An additional approach to improving the splash resistance of face masks is to incorporate a layer of porous, high loft, fibrous material. This type of material is advantageous in that the layer will absorb the energy of the impact of the fluid splash. However, it is often the case that fluid will saturate this high loft material, hence reducing its effectiveness in absorbing the energy of a future fluid splash. Additionally, fluid can be squeezed out of this high loft material and may be transferred through subsequent layers upon compression of the face mask.
A perforated film incorporated into a face mask is shown in U.S. Pat. No. 4,920,960 (incorporated herein in its entirety for all purposes) may be used in order to provide a fluid barrier to the face mask while still allowing for the user to be able to breath through the perforations in the film.
In some face masks, a layer of point bonded polyolefin, typically a polypropylene spunbond, may be positioned on either side of a filtration media layer to improve splash resistance.
The present invention provides an additional approach to imparting splash resistance to a face mask.